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The present study aimed to investigate the influence of months of birth on anthropometry, body composition, biological maturation, and motor performance in young Brazilian soccer players. Young Brazilian soccer players from the Under-13 (n = 50; 13.6 ± 0.3 years), Under-15 (n = 50; 15.5 ± 0.4 years), and Under-17 categories (n = 46; 17.7 ± 0.3 years) took part in this study. Athletes were divided according to chronological age, 1st tertile (January to April); 2nd tertile (May to August); and 3rd tertile (September to December). Anthropometry, body composition, biological maturation, and motor performance variables were evaluated for all participants. There were no differences between the U-13, U-15, and U-17 categories regarding birth tertiles (p > 0.05). Differences between the ages and birth tertiles were observed for the stature, body mass, and lean body mass (p < 0.05). Moreover, differences were found in maturational status between the ages and birth tertiles (p < 0.05). In general, U-13 players showed lower values compared to U-15 and U-17 players in tests of motor performance. In addition, there was a difference in motor performance between the birth tertiles only for RSA variables. The months of birth influenced the stature, body mass, lean body mass, and repeated sprint ability in the U-13 and U-15 categories. Thus, care should be taken during the process of talent selection, as many young players could be underestimated due to their date of birth.

Obesity is related to negative changes in insulin resistance and liver enzymes and is associated with the risk factor for the development of type II diabetes mellitus and nonalcoholic fatty liver disease. A number of studies have demonstrated that aerobic exercise shows promise for disease prevention and treatment in this population. The objective of the present study was to evaluate the effect of a walking exercise program with self-selected intensity on insulin resistance and liver enzymes in obese women. Forty-eight obese women (47.8 ± 8.4 years; 88.1 ± 12.0 kg; 158.0 ± 0.1 cm) were divided into two groups: control group (CG; n = 23) and self-selected walking group (SSWG; n = 25). Before and after the exercise program, all subjects underwent anthropometric measurements and blood samples were collected. The intervention consisted of a walking exercise program with self-selected intensity for 12 weeks (3 times/week, totalizing 36 sessions). After the exercise program, fasting glucose, fasting insulin, and HOMA improved only in the SSWG (p 0.05). In addition, there were no differences in liver enzymes after the intervention in both groups (p > 0.05). The results support that a walking exercise program with self-selected intensity improved insulin resistance in obese women. Thus, exercise programs with self-selected intensity seem to be an interesting alternative for improving health and preventing diseases.

Background Transcranial direct current stimulation (tDCS) has been used to improve exercise performance, though the protocols used, and results found are mixed. Objective We aimed to analyze the effect of tDCS on improving exercise performance. Methods A systematic search was performed on the following databases, until December 2017: PubMed/MEDLINE, Embase, Web of Science, SCOPUS, and SportDiscus. Full-text articles that used tDCS for exercise performance improvement in adults were included. We compared the effect of anodal (anode near nominal target) and cathodal (cathode near nominal target) tDCS to a sham/control condition on the outcome measure (performance in isometric, isokinetic or dynamic strength exercise and whole-body exercise). Results 22 studies (393 participants) were included in the qualitative synthesis and 11 studies (236 participants) in the meta-analysis. The primary motor cortex (M1) was the main nominal tDCS target (n = 16; 72.5%). A significant effect favoring anodal tDCS (a-tDCS) applied before exercise over M1 was found on cycling time to exhaustion (mean difference = 93.41 s; 95%CI = 27.39 s–159.43 s) but this result was strongly influenced by one study (weight = 84%), no effect was found for cathodal tDCS (c-tDCS). No significant effect was found for a-tDCS applied on M1 before or during exercise on isometric muscle strength of the upper or lower limbs. Studies regarding a-tDCS over M1 on isokinetic muscle strength presented mixed results. Individual results of studies using a-tDCS applied over the prefrontal and motor cortices either before or during dynamic muscle strength testing showed positive results, but performing meta-analysis was not possible. Conclusion For the protocols tested, a-tDCS but not c-tDCS vs. sham over M1 improved exercise performance in cycling only. However, this result was driven by a single study, which when removed was no longer significant. Further well-controlled studies with larger sample sizes and broader exploration of the tDCS montages and doses are warranted.

To evaluate the effects of 12-weeks of walk training with self-selected intensity on lipid profile and anthropometric variables in women with obesity. Forty-eight women volunteers with obesity were randomly assigned into two training groups: self-selected walking group (SSWG; n=25) and control group (CG; n=23). There was improvement in biochemical markers only in the SSWG post-intervention (p0.05), however no changes were verified in anthropometric variables (p0.05). This study demonstrates that walking at self-selected intensity improved the lipid profile in women with obesity.

Aim: To investigate the effects of low-intensity walk training with and without blood flow restriction (BRF) on resting heart rate variability (HRV) and blood pressure (BP) in middle-aged men. Methods: Twenty-one men were randomly assigned into the walk training group with (BRF-W; n = 11) and without (NOR-W; n = 10) BFR. The resting HRV and blood pressure were assessed pre- and post-6 weeks of the intervention [3 times/week, 5 sets of 3-min walking (6 km.h-1) with 1-min of rest, totalizing 18 sessions of training]. The BFR-W group received the occlusive stimulus before of training sessions though of a standard sphygmomanometer and performed the training sessions with the vascular occlusion (80-100 mmHg) in both the legs. Results: Only BRF-W group improved HRV on time domain indices (SDNN and RMSSD; p < 0.05) after training but it was not found differences on frequency domain indices. In addition, systolic blood pressure (SBP) improved after training (PRE: 128.5 ± 5.9 vs POST: 119.1 ± 8.6 mmHg; Cohen’s d = -1.30; p < 0.01) only in BFR-W group. There was not a significant difference on diastolic blood pressure (DBP) after training, however, effect size was moderate for BFR-W (Cohen’s d = -0.56; p > 0.05). Conclusion: Our results showed that walking training with blood flow restriction can improve health cardiovascular parameters in middle-aged men.

Resumo A autopercepção de saúde tem demonstrado estreita relação com indicadores de morbidade e mortalidade. Em funcionários de hospitais existe uma escassez acerca destas informações, por isso o objetivo deste estudo foi verificar a prevalência de satisfação com a saúde em trabalhadores de um Hospital Universitário (HU) e sua associação com indicadores de adiposidade, pressão arterial (PA) e de atividade física (AF). Participaram do estudo 380 adultos entre 20 e 59 anos com idade média de 43,92 (DP = 8,46) anos. A autopercepção de saúde foi avaliada mediante uma questão extraída do questionário “WHOQOL-bref”. A satisfação com a saúde foi de 60,8%, e as mulheres declararam estar menos satisfeitas. A análise ajustada pelo sexo indicou que apresentar IMC eutrófico se associou com a maior ocorrência de satisfação com a saúde (RP = 1,478 [IC 95%: 1,272 – 1,717]) seguido pela CC (RP = 1,323 [IC 95%: 1,135 – 1,541]). A PA e a AF não se associaram à autopercepção de saúde. Conclui-se que os trabalhadores do HU reconhecem os riscos à sua saúde, todavia negligenciam a importância de manter valores pressóricos adequados e ter uma prática regular de AF com o intuito de postergar o surgimento de alguma condição crônica que seja maléfica ao organismo. Abstract It has been shown that self-perceived health has a close relationship with indicators of morbidity and mortality. Since there is a lack of information on the self-perceived health status of hospital workers, the objective of this study was to determine the prevalence of satisfaction with health among people working at a University Hospital (UH) and its associations with indicators of adiposity, arterial blood pressure (BP) and physical activity (PA). A total of 380 adults took part in the study, with ages ranging from 20 to 59 and a mean age of 43.92 (SD = 8.46) years. Self-perceived health was assessed using a question from the “WHOQOL-bref” questionnaire. Overall satisfaction with health was 60.8%, and women reported lower satisfaction than men. An analysis adjusted for sex showed that having a healthy BMI was associated with the highest rate of satisfaction with health (PR = 1.478 [95%CI: 1.272 – 1.717]), followed by WC (PR = 1.323 [95%CI: 1.135 – 1.541]). Neither BP nor PA were associated with self-perceived health. It was concluded that the UH workers are aware of risks to their health, but that they do not recognize the importance of maintaining healthy blood pressure or of engaging in regular PA in order to delay onset of chronic conditions that could be harmful to them.

Aims: The purpose of this study was to examine the effects of training volume (1 vs. 3 sets) on lower-body muscle strength in untrained young men. Methodsː Eighteen untrained young men were recruited and their legs were trained with 1 or 3 sets (in a contralateral design) for 6 weeks, using a knee extension machine. Isokinetic peak torque and one repetition maximum (1RM) were assessed at pre- and post-training. Resultsː There was a similar improvement in the 1RM strength (1SET: +14.8% vs. 3SET: 16.3%, P > 0.05) and peak torque (1SET: +8.1% vs. 3SET: 9.3%, P > 0.05) for both conditions from pre- to post-training. The effect size (ES) for the change in 1RM was moderate for both conditions (1SET: 1.39 vs. 3SET: 1.41), and peak torque was trivial and small for 1SET (0.47) and 3SET (0.55), respectively. Additionally, there were no significant (P > 0.05) differences in the dietary intakes from pre- to post-training. Conclusionsː Our results indicate that 1 set is as effective as 3 sets for increasing lower-body muscle strength after a short-term RT period (6 weeks) in untrained young men.

BACKGROUND: Differences related to sexual characteristics are directly linked to the mechanisms responsible for adaptations from resistance training (RT). Due to these differences, men and women may perform their RT programs at different percentages of maximum strength even when executing the same number of repetitions. OBJECTIVE: To compare the relative repetition maximum (%1RM) at which men and women perform RT in a program controlling repetitions/set. METHODS: Thirty men (22.7 ± 4.4 years, 68.4 ± 9.0 kg, 174.5 ± 6.6 cm), and 34 women (22.7 ± 4.1 years, 58.8 ± 11.9 kg, 162.6 ± 6.2 cm) performed 16 weeks of RT, 3 times per week using 3 sets of 8–12 RM. Anthropometric measurements and 1RM test in bench press (BP), and arm curl (AC) were obtained at baseline and after the RT program. RESULTS: Women performed the training in BP at a higher %1RM than men ( P 0.05). There was not significant main effect for AC ( P> 0.05) indicating no change in %1RM at which each sex exercised. CONCLUSION: We conclude that men and women perform RT at different %1RM in BP, except for the AC during a RT program utilizing 8–12 RM per set.

OBJETIVO: O presente estudo verificou os efeitos da suplementação com cafeína associada ao exercício físico agudo sobre a resposta glicêmica em ratos diabéticos. MÉTODOS: Foram utilizados 32 animais, com 60 dias de idade, e 238±3 g de peso, divididos em quatro grupos: controle, controle cafeína, diabetes e diabetes/cafeína. O modelo de diabetes foi induzido pela administração intraperitoneal de 60 mg/kg de estreptozotocina. De forma aguda, os animais receberam 6 mg de cafeína ou salina para os grupos-controles 60 minutos antes do exercício físico. Os animais realizaram um protocolo de natação de 60 minutos de exercício físico, com sobrecarga de 6% do peso corporal com lactacidemia compatível com a máxima produção de lactato em estado estável (5,5 mmol/L). Após o exercício físico agudo, foi realizada a eutanásia dos animais para coleta de sangue e análises glicêmicas. Antes e após a prescrição das suplementações, ocorreu a aferição das respostas cardiovasculares por meio de um pletismógrafo de cauda. Foi realizado o teste estatístico Analise de Variância one way com post hoc de Student-Newman-Keuls para analisar as diferenças estatísticas entre as suplementações, sendo considerado p

The main purpose of the present study was to investigate the effect of 16 weeks of resistance training (RT) on body water in men and women. Thirty men (22.7 ± 4.4 years, 68.4 ± 9.0 kg and 174.5 ± 6.6 cm) and 34 women (22.7 ± 4.1 years, 58.8 ± 11.9 kg and 162.6 ± 6.2 cm) underwent progressive RT for 16 weeks (2 phases, 8 weeks each), 3 times per week, that consisted of 10-12 whole body exercises with 3 sets of 8-12 repetitions maximum. Total body water, TBW (intracellular water, ICW and extracellular water, ECW compartments) and skeletal muscle mass (SMM) were assessed using a spectral bioelectrical impedance device (Xitron 4200 Bioimpedance Spectrum Analyzer). TBW, ICW compartment and SMM increased significantly (P0.05) over time in men (+7.5%, +8.2% and +4.2%, respectively) and women (+7.6%, +11.0% +3.9%, respectively), with no sex by time interaction (P0.05). We conclude that progressive RT promotes an increase in body water, principally by intracellular content; however, the hydration status is not influenced by sex.

Frequency domain analyses in electromyographic (EMG) signals are frequently applied to assess muscle fatigue and similar variables. Moreover, Fourier-based approaches are typically used for investigating these procedures. Nonetheless, Fourier analysis assumes the signal as stationary which is unlikely during dynamic contractions. As an alternative method, wavelet-based treatments do not assume this pattern and may be considered as more appropriate for joint time-frequency domain analysis. Based on the previous statements, the purpose of the present study was to compare the application of Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) to assess muscle fatigue in dynamic exercise of a 1-km of cycling (time-trial condition). The results of this study indicated that CWT and STFT analyses have provided similar fatigue estimates (slope) (p> 0.05). However, CWT application represents lesser dispersion (pp> 0.05) according to different methods, it is important to note that these responses seem to show greater values for CWT compared to STFT for 2 superficial muscles. Thereby, we are capable of considering CWT as a reliable and useful method to take into consideration when non-stationary or oscillating exercise models are evaluated.

O objetivo deste trabalho foi analisar osefeitos do enxágue bucal com carboidrato sobre o desempenho, durante sprints repetidos (RSA), de jovens jogadores de futebol. Nove atletas de futebol dacategoria infantil (15,0 ± 1,5 anos; 60,7 ± 4,84 kg; 1,72 ± 0,05 m; 20,5 ± 1,25kg/m2) foram submetidos ao teste de RSA. O teste foi composto por seis sprintsde 40 m (ida/volta = 20 m + 20 m), separados por 20 s de recuperação passiva com três condições experimentais: enxágue bucal com carboidrato (CHO) ou placebo (PLA) e controle (CON). O enxágue bucal com CHO ou PLA foi conduzido 5 min antes e imediatamente antes do início dos testes em doses de 100 mL. Otempo do melhor sprint (RSAbest), a média de tempo dos sprints (RSAmean) e o índice de fadiga (IF) foram determinados nas diferentes condições experimentais. ANOVA one-way para medidas repetidas não identificou diferenças significantes (p> 0,05) para RSAbest (CHO = 7,30 ± 0,31 s; PLA = 7,30 ± 0,30 s; CON = 7,26 ±0,16 s), RSAmean (CHO = 7,71 ± 0,30 s; PLA = 7,71 ± 0,25 s; CON = 7,66 ± 0,24s) e IF (CHO = 5,58 ± 2,16%; PLA = 5,77 ± 3,04%; CON = 5,55 ± 3,72%). Os resultados sugerem que o enxágue bucal com CHO não parece capaz de melhorar odesempenho, sobre sprints repetidos, de jovens jogadores de futebol

The aims of this study were to verify the relationship between rating of perceived exertion (RPE) and electromyography (EMG) increases during exhaustive constant-load cycling bouts and, to compare and to correlate the power outputs corresponding to perceived exertion threshold (PET) and neuromuscular fatigue threshold (NFT). 11 men completed 3-4 different exhaustive constant-load cycling bouts on a cycle ergometer, being RPE and EMG measured throughout the bouts. The linear regression of the RPEslope and EMGslope against the power output identified the PET and NFT intensity, respectively. There was a significant relationship between RPEslope and EMGslope (R(2)=0.69; P

O objetivo do presente estudo foi investigar o impacto de oito semanas de suplementação de creatina mono-hidratada (Crm) sobre o desempenho anaeróbio de adultos jovens treinados. Vinte e seis estudantes de educação física, do sexo masculino, saudáveis, foram divididos aleatoriamente em grupo creatina (GCr, n = 13; 22,5 ± 2,7 anos; 74,9 ± 6,8kg, 178,5 ± 4,8cm) e grupo placebo (GPl, n = 13; 22,9 ± 3,2 anos, 71,9 ± 11,3kg, 178,6 ± 4,0cm). Os indivíduos ingeriram em sistema duplo-cego doses de Crm ou placebo-maltodextrina (20 g.d-1 por 5 dias e 3 g.d-1 por 51 dias subsequentes). Ambos os grupos tiveram seus hábitos alimentares e os níveis de aptidão física controlados anteriormente. O teste anaeróbio de Wingate (TW) foi usado para avaliar o desempenho anaeróbio antes e após o período de ingestão de Crm ou placebo. Os índices de desempenho analisados foram: potência pico relativa (PPR), potência média relativa (PMR), trabalho total relativo (TTR) e índice de fadiga (IF). Para tratamento estatístico foi utilizado ANOVA, seguido pelo teste de post hoc Tukey, quando P

The purpose of this study was to compare back muscle fatigue of younger and older participants with and without chronic low back pain (CLBP). Twenty participants without and 20 with nonspecific CLBP participated in this study. Each group contained 10 younger (50% males; mean age: 31 ± 6 yrs) and 10 older adults (50% males; age mean: 71 ± 7 yrs). Two isometric fatigue protocols were presented randomly: (1) to maintain the unsupported trunk at the horizontal position while on a 45° Roman chair for a minute, and (2) to maintain a 10% of body weight box close to the trunk in the upright position for a minute. Surface electromyography (EMG) signals from the back (multifidus and iliocostalis) and one hip (biceps femoris) muscles were recorded bilaterally, and the median frequency fatigue estimate from linear regression slopes of the EMG time-series was computed. There were no significant (P > 0.05) age effects, and group-by-age interaction in both isometric and functional fatigue tasks. However, the CLBP groups (both younger and old) displayed more back fatigue than people without CLBP in both fatigue protocols (P < 0.01; effect size varying of d = 0.17-0.32). This study was sensitive to discriminate that individuals with CLBP did present significantly more pronounced EMG back fatigue than people without CLBP, in both younger and older adults. These results have significant clinical implications for low back pain rehabilitation programs with regard to endurance assessment in both younger and older.

The purpose of this study was to examine the effects of acute l-arginine (l-arg) supplementation on peripheral vasodilatation and muscle performance in older women. In a double-blind, randomized, placebo-controlled study, 20 elderly women were randomly assigned in a double-blind fashion to either an l-arg (ARG, N = 10) or placebo (PLA, N = 10) group. During the first visit, both groups underwent a Doppler ultrasound exam (to assess the femoral artery vasodilatation) at rest (baseline), and immediately before and after the isokinetic strength test (performed at 80 min after supplementation). On the second and third visits, the groups completed a battery of muscle performance tests (to assess the isometric and functional strength), initiated at the same time point (80 min after supplementation). The femoral artery blood flow (ARG: 443.9 ± 42.8 vs. PLA: 373.1 ± 40.8 ml/min; P > 0.05) and area (ARG: 0.45 ± 0.03 vs. PLA: 0.41 ± 0.02 cm2; P > 0.05) were similar between the groups at basal conditions, and they remained unchanged after supplementation. Following exercise, blood flow increased ~160 % above the basal level, and there was no significant (P > 0.05) difference between the ARG and PLA groups. Additionally, there were no significant (P > 0.05) differences between the ARG and PLA groups for any strength variable (isokinetic, isometric, and functional). These results show that acute l-arg supplementation provides no ergogenic effect on blood flow and muscle performance in older women.

Ergogenic effect of caffeine on performance in middleand long- term exercise Caffeine is a substance that does not have a nutritional value being classified as a pharmacological active alkaloid, with stimulating action on central nervous system (CNS). However, this substance has been considered a nutritional ergogenic, since it is present in several drinks consumed daily, such as coffee, chocolate, teas and some soft drinks with guarana. Its use has been common in sports, specially in last years, particularly for athletes in cycling competitions and middle- and long-distance runners. The ergogenic effect of caffeine on performance has been demonstrated after the acute ingestion of doses of caffeine between 3 and 6 mg/kg of body weight. However, it is not still clear which action mechanisms of caffeine would be involved on performance improvement of long-term exercise. The supposed diuretic effect induced by the use of caffeine has not been confirmed in practice, and it seems that it is related to employment of mega-doses of this substance. Recently, caffeine was removed of the list of the prohibited substances by the World Agency Anti-Doping (WADA). This probably implies a considerable increase of its use by athletes. Thus, it is necessary some cares when using this ergogenic substance, since the disoriented ingestion may contribute to the emergence of collateral effects influencing negatively athlete’s performance.

The purpose of this study was to investigate the effect of hypertrophy-type resistance training (RT) on upper limb fatigue resistance in young adult men and women. Fifty-eight men (22.7±3.7 years, 70.6±9.3 kg, and 176.8±6.4 cm) and 65 women (21.6±3.7 years, 58.8±11.9 kg, and 162.6±6.2 cm) underwent RT for 16 weeks. Training consisted of 10-12 whole body exercises with 3 sets of 8-12 repetitions maximum performed 3 times per week. Before and after the RT intervention participants were submitted to 1RM testing, as well as a fatigue protocol consisting of 4 sets at 80% 1RM on bench press (BP) and arm curl (AC). The sum of the number of repetitions accomplished in the 4 sets in each exercise was used to indicate fatigue resistance. There was a significant (p

This research investigated the effects of music and its time of application on a 5-km run. Fifteen well-trained male long-distance runners (24.87 ± 2.47 years; 78.87 ± 10.57 kg; 178 ± 07 cm) participated in this study. Five randomized experimental conditions during a 5-km run on an official track were tested (PM: motivational songs, applied before 5 km of running; SM: slow motivational songs, applied during 5 km of running; FM: fast and motivational songs, applied during 5 km of running; CS: calm songs, applied after 5 km of running; CO: control condition). Psychophysiological assessments were performed before (functional near-infrared spectroscopy, heart rate variability [HRV], valence, and arousal), during (performance time, heart rate, and rate of perceived exertion [RPE]), and after (mood, RPE, and HRV) tests. The chosen songs were considered pleasurable and capable of activating. Furthermore, they activated the 3 assessed prefrontal cortex (PFC) areas (medial, right dorsolateral, and left dorsolateral) similarly, generating positive emotional consequences by autonomous system analysis. The first 800 m was accomplished faster for SM and FM compared with other conditions (p ≤ 0.05); moreover, there was a high probability of improving running performance when music was applied (SM: 89%; FM: 85%; PM: 39%). Finally, music was capable of accelerating vagal tonus after 5 km of running with CS (p ≤ 0.05). In conclusion, music was able to activate the PFC area, minimize perceptions, improve performance, and accelerate recovery during 5 km of running.

Caffeine can stimulate insulin secretion by attenuating hyperglycemia in diabetes models with significant reduction of pancreatic functional β cells. Knowledge of these mechanisms could contribute to new strategies for treating diabetes.This study evaluated the effects of caffeine and physical exercise on glycemic and insulin responses in diabetic rats.The diabetes model was induced by intraperitoneal administration of 60 mg/kg of streptozotocin (STZ). Animals were divided into six groups: control, caffeine, STZ control, STZ caffeine, STZ sulfonylurea, and STZ caffeine + sulfonylurea. Acutely, control animals received 6 mg of caffeine and 10 mg/kg sulfonylurea or 10 mg/kg saline. Animals were sacrificed after physical exercise; blood samples were collected for glucose, glycerol, lactate, and insulin analyses. Cardiovascular responses were recorded before and after treatments. A one-way ANOVA and the post hoc Student-Newman-Keuls test were used to analyze statistical differences between treatments (p 0.05).About 6 mg/kg of caffeine did not alter cardiovascular responses, but promoted blood glucose reduction after 60 min of exercise when compared to animals in the control groups (387-187 mg/dL; p 0.05). Insulin levels increased significantly (0.6-10 µU/mL; p 0.05) in rats that received acute caffeine treatment associated with sulfonylurea compared to rats in the other groups.Acute caffeine intake with exercise can increase glucose uptake enhancing insulin secretion stimulated by sulfonylurea in β cells-deficient pancreas. The results indicate the potential use of caffeine as a strategy for glycemic and insulin control in diabetes.

Camata, TV, Altimari, LR, Bortolotti, H, Dantas, JL, Fontes, EB, Smirmaul, BPC, Okano, AH, Chacon-Mikahil, MPT, and Moraes, AC. Electromyographic activity and rate of muscle fatigue of the quadriceps femoris during cycling exercise in the severe domain. J Strength Cond Res 25(9): 2537-2543, 2011-This study compared the activation pattern and the fatigue rate among the superficial muscles of the quadriceps femoris (QF) during severe cycling exercise. Peak oxygen consumption (VO peak) and maximal accumulated oxygen Deficit (MAOD) were established by 10 well-trained male cyclists (27.5 ± 4.1 years, 71.0 ± 10.3 kg, 173.4 ± 6.6 cm, mean VO peak 56.7 ± 4.4 ml·kg min , mean MAOD 5.7 ± 1.1 L). Muscle activity (electromyographic [EMG] signals) was obtained during the supramaximal constant workload test (MAOD) and expressed by root mean square (RMS) and median frequency (MF slope). The RMS of the QF, vastus lateralis (VL) and vastus medialis (VM) muscles were significantly higher than at the beginning after 75% of exercise duration, whereas for the rectus femoris (RF), this was observed after 50% of exercise duration (p ≤ 0.05). The slope of the MF was significantly higher in the RF, followed by the VL and VM (23.13 ± 0.52 vs. 22.61 ± 0.62 vs. 21.81 ± 0.56, respectively; p < 0.05). We conclude that RF may play an important role in limiting performance during severe cycling exercise.

The objective of this study was to investigate possible differences in the EMG signal spectral analysis of the superficial quadriceps muscles, using the techniques short-time Fourier transform (STFT) and continues Wavelet (CWT) db4 type during constant load submaximal cycling exercise. Fourteen male subjects, healthy and physically active (25.8 ± 3.3 years, 82.1 ± 7.3 kg, 181.3 ± 5.5 cm) were submitted to constant load submaximal test (Tcons) with exercise intensity corresponding to 80% of maximum load until voluntary exhaustion. The EMG of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) of the right leg were recorded throughout the period of the Tcons to obtain the parameters: median frequency (MF), fatigue index EMG (FIslp) and variance of MF. The results showed no statistically significant differences for the variables MF, FIslp and variance of MF in any of the muscles examined in different time periods, when comparing STFT and CWT (P> 0.05). Thus, our findings suggest the use of both analytical techniques in constant load submaximal cycling exercise when the target is to quantify muscle fatigue with EMG spectral indicators.

Frequency domain analyses of changes in electromyographic (EMG) signals over time are frequently used to assess muscle fatigue. Fourier based approaches are typically used in these analyses, yet Fourier analysis assumes signal stationarity, which is unlikely during dynamic contractions. Wavelet based methods of signal analysis do not assume stationarity and may be more appropriate for joint time-frequency domain analysis. The purpose of this study was to compare Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) in assessing muscle fatigue in supramaximal constant load dynamic exercise (110% VO2peak). The results of this study indicate that CWT and STFT analyses give similar fatigue estimates (slope of median frequency) in supramaximal constant load dynamic exercise (P>0.05). However, the results of the variance was significantly lower for at least one of the muscles studied in CWT compared to STFT (P

The objective of this study was to investigate the ergogenic effects of caffeine on motor performance of judo female athletes. Thirteen female athletes (17.6 ± 1.6 years, 58.3 ± 11.4 kg, 162 ± 4.1 cm, 22.5 ± 4 kg/m2), registered in the State Federation of Judo for at least two years, participated in this study. The motor performance was assessed using the Special Judo Fitness Test (SJFT), from which was considered the number of throws in each block, the total number of throws, recovery and final heart rate (HR) and final score in SJFT. The subjects were tested in two different conditions, after ingestion of gelatin capsules of caffeine (6 mg.kg-1) or placebo (dextrose) 60 minutes before testing in a randomized double-blind, crossover study. The number of throws in each block did not differs between the caffeine (CAF) and placebo (PL) conditions (Block A: 4.53 ± 0.51 CAF and 4.46 ± 0.51 PL; Block B: 8.3 ± 0.63 CAF and 8.23 ± 0.72 PL; Block C: 7.23 ± 0.59 CAF and 7.46 ± 0.77 PL), as well as the total number of throws (20.07 ± 1.18 CAF and 20.15 ± 1.67 PL), HR (Final: 190.3 ± 9.63 bpm CAF and 190.69 ± 9.19 bpm PL; Recovery 162.07 ± 13.78 bpm CAF and 164.3 ± 9.64 bpm PL) and final score in SJFT (17.59 ± 1.4 CAF and 17.75 ± 1.98 PL). Ingestion of caffeine did not improve performance during high intensity and short duration exercise in judo fighters

Frequency domain analyses of changes in electromyographic (EMG) signals over time are frequently used to assess muscle fatigue. Fourier based approaches are typically used in these analyses, yet Fourier analysis assumes signal stationarity, which is unlikely during dynamic contractions. Wavelet based methods of signal analysis do not assume stationarity and may be more appropriate for joint time-frequency domain analysis. The purpose of this study was to compare Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) in assessing muscle fatigue in isometric and dynamic exercise. The results of this study indicate that CWT and STFT analyses give similar fatigue estimates (slope of median frequency) in isometric and dynamic exercise (P>0.05). However, the results of the variance was lower for both types of exercise in CWT compared to STFT (P

The aim of this study was to evaluate the effect of caffeine intake on critical power model parameters determined on a cycle ergometer. Eight male subjects participated in this study. A double-blind protocol consisting of the intake of pure caffeine (6 mg/kg) or placebo (maltodextrin) 60 min before testing was used. Subjects were submitted to four constant-load tests on a cycle ergometer. These tests were conducted randomly in the caffeine and placebo groups [checar] at intensities of 80, 90, 100 and 110% maximum power at a rate of 70 rpm until exhaustion to determine the critical power. As a criterion for stopping the test was adopted any rate fall without recovery by more than five seconds. The critical power and anaerobic work capacity were obtained by nonlinear regression and fitting of the curve to a hyperbolic power-time model. The Shapiro-Wilk test and paired Student t-test were used for statistical analysis. No significant differences in critical power were observed between the caffeine and placebo groups (192.9 ± 31.3 vs 197.7 ± 29.4 W, respectively). The anaerobic work capacity was significantly higher in the caffeine group (20.1 ± 5.2 vs 16.3 ± 4.2 W, p

The purpose of the present study was to identify the anthropometric and motor performance profi le of futsal (indoor soccer) athletes in the second and third-placed teams in the Parana state championships (Brazil). Anthropometric(body mass, stature and skinfolds thickness) and motor performance (modified abdominal test, shuttle run, race of 30 m and 40 s) measures were obtained from twenty-seven male athletes (24.7 ± 6.4 years; 73.6 ± 7.6 kg; 174.8 ± 6.6 cm). For data analysis, athletes were grouped according to game positions. ANOVA one-way was used for comparisons between different positions, followed by Scheffe’s post hoc test, with p < 0.05. Signifi cant differences were detected in body mass (midfielder < goalkeeper, p < 0.01), stature (midfielder < forward and goalkeeper, p < 0.01) and lean body mass (midfi elder < goalkeeper, p < 0.01). No significant differences in motor performance were detected between the athletes studied. The results of this study show that futsal athletes playing in different positions exhibit similar anthropometric and motor performance, in the majority of variables.

Background The objective of this study was to analyze the effect of caffeine ingestion on the performance and physiological variables associated with fatigue in 20-km cycling time trials. Methods In a double-blind placebo-controlled crossover study, 13 male cyclists (26 ± 10 y, 71 ± 9 kg, 176 ± 6 cm) were randomized into 2 groups and received caffeine (CAF) capsules (6 mg.kg−1) or placebo (PLA) 60 min before performing 20-km time trials. Distance, speed, power, rpm, rating of perceived exertion (RPE), electromyography (EMG) of the quadriceps muscles and heart rate (HR) were continuously measured during the tests. In addition, BRUMS questionnaire was applied before and after the tests. Results Significant interactions were found in power and speed (P = 0.001), which were significantly higher at the end of the test (final 2 km) after CAF condition. A main effect of time (P = 0.001) was observed for RPE and HR, which increased linearly until the end of exercise in both conditions. The time taken to complete the test was similar in both conditions (PLA = 2191 ± 158 s vs. CAF = 2181 ± 194 s, P = 0.61). No significant differences between CAF and PLA conditions were identified for speed, power, rpm, RPE, EMG, HR, and BRUMS (P > 0.05). Conclusion The results suggest that caffeine intake 60 min before 20-km time trials has no effect on the performance or physiological responses of cyclists.